C.3.2.1 DOT rules prohibit cylinders from being refilled, continued in service, or transported unless they are properly qualified or requalified for LP-Gas service in accordance with DOT regulations.
C.3.2.2 DOT rules require a careful examination of every cylinder each time it is to be filled, and it must be rejected if there is evidence of exposure to fire, bad gouges or dents, seriously corroded areas, leaks, or other conditions indicating possible weaknesses that might render it unfit for service. The following disposition is to be made of rejected cylinders:
Cylinders subjected to fire are required to be requalified, reconditioned, or repaired in accordance with C.3.3 or permanently removed from service, except that DOT 4E (aluminum) cylinders and composite material cylinders used under a special permit issued by DOT must be permanently removed from service.
Cylinders showing serious physical damage or leaks or showing a reduction in the marked tare weight of 5 percent or more are required to be retested in accordance with C.3.2.4(1) or C.3.2.4(2) and, if necessary, repaired in accordance with C.3.3.
C.3.2.3 All cylinders, including those apparently undamaged, are required to be periodically requalified for continued service. The first requalification for a new cylinder is required within 12 years after the date of manufacture. Subsequent requalifications are required within the periods specified under the requalification method used. Composite material cylinders used under a special permit issued by DOT must be requalified in accordance with the terms of the permit.
C.18.104.22.168 External Visual Inspection Method. The recorded external visual inspection method can be used to requalify cylinders for 5 years before the next qualification is due, provided the cylinder has been used exclusively for LP-Gas commercially free of corroding components. Inspection is to be made by a competent person, using CGA Standard for Visual Inspection of Steel Compressed Gas Cylinders (CGA Publication C-6) for steel cylinders and CGA Guidelines for Visual Inspection and Requalification of Low Pressure Aluminum Compressed Gas Cylinders (CGA Publication C-6.3) for aluminum cylinders, and recording the inspection results as required by DOT regulations.
The following disposition is to be made of cylinders inspected in this manner:
Cylinders that pass the visual examination are marked with the retester identification number (RIN) and retest date and year of the examination, followed by an E (e.g., 6-07 A123 E, indicating requalification by the specific cylinder retester using the visual examination method in June 2007), and can be placed back into service. In certain situations, DOT has issued visual requalifier identification numbers. Those issued this identification must place the VRIN in a straight line (e.g., V108231), followed by the month and year and the letter E.
Cylinders that leak or show serious denting or gouging or excessive corrosion must be either scrapped or repaired in accordance with C.3.3.